Manitowoc

Liquid Line ThermistorQM20/QM30/SM50FunctionThe liquid line thermistor senses the refrigeration systemliquid line temperature. This is used in conjunction with thecontrol board to determine the length of the freeze andharvest cycles.Specifications10,000 Ohms 2% at 25°C (77°F)! CautionUse only Manitowoc thermistors.Check ProcedureThermistors generally fail because of moisture or physicaldamage. Manitowoc liquid line thermistors are encased in aspecially designed, moisture-sealed aluminum block. Thiseliminates physical damage and moisture concerns.Verify that the thermistor resistance is accurate andcorresponds to the high and low temperature ranges.1. Disconnect the thermistor at the control board. Connectthe ohmmeter to the isolated thermistor wire leads.2. Using a temperature meter capable of taking readingson curved copper lines, attach the temperature metersensingdevice to the liquid line next to the thermistoraluminum block.ImportantDo n ot simply “in sert” the sensing devi ce und erthe insulation. It must b e attached to and readingthe actual temperature of the copper liquid line.3. With the ice machine running, verify that thetemperature of the discharge line (step 2) correspondsto the thermistor resistance reading (step 1) as stated inthe temperature/resistant chart.ImportantIf the thermistor would fail closed, the light on thecontrol board will flash rapidly.If th e thermistor woul d fail open , the ligh t on thecontrol board will flash slowly.Part Number 80-01111-9 7/10 169